postgres_tests fail ungracefully if psycopg2 isn't installed

[Aymeric Augustin]

Uninstalling psycopg2 and running ./runtests.py postgres_tests shows a series of stack traces.

Would it be possible to make the imports conditional and skip the tests cleanly?

See template_backends/test_jinja2.py for an example.

[Joel Burton]

Patch

[Joel Burton]

Added conditional import for psycopg2 and @skipIf on tests.

[Tim Graham]

There is a new problem on master (which affects 1.8 too, but it's a RemovedInDjango19Warning instead of a RuntimeError:

$ ./runtests.py postgres_tests
...
Model class postgres_tests.models.IntegerArrayModel doesn't declare
an explicit app_label and either isn't in an application in INSTALLED_APPS
or else was imported before its application was loaded.

It's caused by the ​hack in runtests.py to omit the postgres_tests app when not running with a postgresql database (to avoid trying to apply the migrations when not in postgresql). I'm attaching a patch I experimented with, but there are still unsolved problems with it.

[Claude Paroz]

Also encountered:

  File "/home/claude/virtualenvs/djangogit/local/lib/python2.7/site-packages/django/contrib/postgres/forms/ranges.py", line 1, in <module>
    from psycopg2.extras import DateRange, DateTimeTZRange, NumericRange
ImportError: cannot import name DateRange

>>> psycopg2.__version__
'2.4.5 (dt dec mx pq3 ext)'

It might also depend on installed PostgreSQL extensions.

[Claude Paroz]

Created #24335 for the DateRange import failure.

[Tim Graham]

After looking into this a bit more (trying to remove the hack in runtests.py), I think it might be a better use of time to just skip postgres_tests entirely when not testing with the django.db.backends.postgresql_psycopg2 backend. While it's nice in theory to allow executing the non-database tests while testing with other backends, in practice it seems quite convoluted. Objections?

Maybe a separate test app (without any models) would be the way to go if there's a strong incentive to allow that.

[Tim Graham]

​PR to skip postgres_tests if not running with PostgreSQL.

[Tim Graham <timograham@…>]

In 8b39f33d78ce5749f8ca40a7ae6823b5f6c26c09:

Fixed #24290 -- Skipped postgres_tests if not running with PostgreSQL.

[Tim Graham <timograham@…>]

In a00a0f880485e1f122e48e0216d34d08efe199e1:

[1.8.x] Fixed #24290 -- Skipped postgres_tests if not running with PostgreSQL.

Backport of 8b39f33d78ce5749f8ca40a7ae6823b5f6c26c09 from master